Electric circuit breaker



Nov. 23, 1943.

1.. J. LiNDE 2,335,068

ELECTRIC CIRCUIT BREAKER Filed March 20, 1942 //vs UL A TI 0N Inventor:

Leonard 3'. Linda,

His Attorney.

Patented Nov. 23, 1943 ELECTRIC omcurr BREAKER Leonard J. Linde, Drexel Hill, la., assignor to General Electric Company, a corporation of New York Application March 20, 1942, Serial No. 435,463

7 Claims. (01. 200-146) My invention relates to electric circuit breakers for interrupting high and moderate voltage power circuits and more particularly to air circuit breakers of the magnetic blowout type having an insulating arc chute.

The use, in high current interrupting capacity air circuit breakers, of so-called primary, secondary and tertiary contacts for normally carrying the load current and for transferring the same to arcing structure upon opening of the breaker has been an accepted practice. The primary contacts are designed to carry the normal load current without overheating but are not subjected to arcing. The secondary contacts are arranged to transfer the power current from the primary contacts upon initial opening of the breaker to the tertiary or arcing contacts. In a well known form of air circuit breaker the arc is driven by a magnetic blowout coil from the tertiary contacts to arcing horns within an insulating arc chute where the arc is extinguished.

However, this arrangement is somewhat complicated and expensive, particularly for smallsize breakers where, although the interrupting capacity is less, the main functions of the contact arrangement above described are still essential.

The principal object of my invention therefore is the provision of an improved air circuit breaker of the aforesaid type having simplified contact and are extinguishing structure that is compact, rugged and inexpensive in construction, and electrically efllcient in operation.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 is an elevational view, partly in section, of a magnetic blowout type air circuitbreaker embodying the present invention; Fig. 2 is an enlarged detail view in section taken along the line 2--2 of Fig. 1; and Fig. 3 is a fragmentary view of the contact arrangement of Fig.1 in a partly open position.

The magnetic blowout type air circuit breaker shown byway of example comprises relatively fixed and movable contact structure I and 2 respectively, the fixed contact structure being connected to the breaker lead-in terminal I and the movable contact structure to the other terminal 2'.' A switch-blade 3 carrying the movable contact'structure is pivotally mounted at I on the terminal 2' and is suitably connected through an operating linkage 5-8 to an operating mechanism (not shown). The circuit breaker is shown in closed circuit position and opening of the breaker is accomplished by clockwise rotation of the blade 3 through its operating mechanism.

The contacts are associated with an insulating arc chute I that is supported in depending relation by the breaker terminals as indicated and is preferably, although not necessarily, of the interleaving barrier type. That is, the inner side walls of the chute facing each other are provided with a number of parallel interleaving ridges or barriers 8 that form between-them a tortuous or zigzag arc passage (as viewed transversely) extending through the chute. .The are formed at the separating contacts enters one end of the chute at 9 and is blown, preferably 'by a magnetic field, transversely of the interleaving ridges into the chute where it is interrupted due to its being greatly lengthened and attenuated. The exhaust end of the chute at I0 is provided with further arc controlling structure lI-l2 for confining the are within the chute while permitting free venting of the exhaust arcv gases. An arc chute of this character is morespeciflcally disclosed and is claimed in my Patent No. 2,293,513, issued August 18, 1942, for Electric air circuit breaker, and assigned to the same assignee as the present invention.

Referring now particularly to the coacting contact and arcing structure, the fixed structure I includes a conducting terminal portion I3 on which is mounted a primary or current-carrying contact I4 and a transfer contact IS. The primary contact I is resiliently mounted and guided, as by a guide pin and spring at it, so as to have a limited amount of wipe when engaged by the movable contact blade 3. One end makes current-carrying line contact at I! with a shoulder on the portion l3, and the opposite or free end is provided with a rounded portion M for also making current-carrying line contact with the movable contact. Accordingly, when the contact I is engaged, it can rotate clockwise against the bias of its spring at l6 for a-limited wipe while still making good electricalcontact at 14' and I! with the movable and fixed contact structures respectively; v

The coacting movable primary contact comprises a plate-like conducting member or insert l8 at the free end ,ofzthe blade 3. Specifically, the blade is formedibya pair of spaced arms I joined at the free end by a conducting block IS on which the primary contact is mounted. The transfer contact l5 above referred to ispivotally mounted at 20 on another shoulder of the terminal portion l3 and is biased counterclockwise by a spring 2! seated in a recess 22 in the terminal P3. In the closed circuit position. shown by Fig. 1 the coacting movable transfer contact 23 engages the contact 15 so as to bias it clockwise'about its current-carrying pivot 20. The aforesaid movable transfer contact 23 is formed at, and preferably by, one end of an arcing horn 24 that is secured to the outer end of the block l9 so as to move as a unit with the movable contact blade. The coaction of the transfer contacts is more clearly shown by Fig. 3 which shows the breaker in a partially closed position.

The contact structure so far described is chiefly for the purpose of carrying heavy load currents without overheating and for transferring the current without arcing from the primary contacts l4 and I8 when the breaker is opened. In accordance with well-known practice, the primary contacts l4 and I8 open first, due to limited following action or wipe at l6, causing transfer of the current to the contacts l5 and 23 which have a longer Wipe. It will be noted that the current paths through the primary and transfer contacts are in parallel so that this transfer is accomplished without arcing.

Referring now to Fig. 3, when the transfer contacts l5 and 23 separate the power are is initially formed. The are must now be handled so that it moves rapidly into the chute without excessive burning of the contact structure. To this end the chute is provided with a fixed arcing horn 25 arranged to cooperate with the movable horn 24. The arcing horns at the point of initial arcing between contacts l5 and 23 are closely spaced from each other by a short air gap, specifically a U-shape gap 26, as illustrated by Fig. 2. This gap is formed between the movable horn 24 and the adjacent side walls of a slot-like recess 25 extending along the arcing face of the fixed horn 25. This slot-like recess within which the movable horn operates extends longitudinally of the horn 25 for a distance and in depth corresponding to the arouate movement of the horn 24.

In accordance. with the above-described arrangement, the arc quickly jumps across the shorter gap 26 to the horn 25 when the movable transfer contact 23 (to which one terminal of the arc is now attached) moves into the slot 25', thereby lengthening the gap between the arcing surfaces at 23 and I5. The fixed horn 25 is electrically connected to the terminal portion l3 in a manner presently described.

The are is now entirely on the diverging arcing horns 24 and 25 and moves into the chute 1 under influence of a magnetic blowout field as the breaker opening progresses. The magnetic blowout arrangement conveniently comprises but a single blowout coil 21 having one terminal connected through a conductor 28 to the terminal portion l3 and the other terminal to the fixed horn 25. The blowout coil and fixed horn are mounted beneath the portion l3 and are normally insulated at 29 from the fixed contact structure. However, when the arc transfers to the horn 25 the blowout coil is energized through the following current path: breaker terminal 2', movable blade 3, arc horn 24, the arc within the gap 28, horn 25, blowout coil 21, conductor 28 and the other breaker terminal I. The blowout field so produced quickly loops the are into the chute where it is extinguished.

In the case of weak arc currents, the blowout field can be supplemented by a "boostez or the like for directing an air jet across the arc as it is initially formed. Such means can comprise a cylinder 30 fixed to the breaker supports and a cooperating movable piston 3lsecured at 32 to the blade 3 by means of a hollow piston rod 33. The hollow piston rod communicates at the piston end with the cylinder 38 and at the opposite end with a jet vent 3 arranged to direct air from the cylinder across the arc as the movable contact opens. This booster arrangement is more specifically disclosed and is claimed in Patent No. 2,280,616, issued April 21, 1942, to R, J. Baskerville, for "Electric circuit breaker, and assigned to the same asslgnee as the present invention.

When the breaker is closed, the transfer contacts 23 ,and i5 engage first, thereby limiting any possible burning to that point, followed by engagement of the primary contacts l8 and I4 to which the main current is transferred.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An eletcric circuit breaker comprising relatively fixed and movable contacts and a fixed arcing horn, said movable contact having a coating arcing horn shaped with respect to said fixed horn so as to be spaced from said fixed arcing horn by an elongated narrow U-shaped gap, said arcing horns diverging from said gap for causing extension and lengthening of the arc therebetween upon opening of said breaker.

2. An electric circuit breaker comprising relatively fixed and movable contacts and a fixed arcing horn, said fixed arcing horn having an elongated slab-like recess, said movable contact having a coacting arcing horn extending therefrom and movable within said slot-like recess in said fixed arcing horn and spaced therefrom to form a narrow U-shaped gap.

3. An electric circuit breaker comprising fixed contact structure including a main current carrying contact and a transfer contact, coacting movable contact structure including a main current carrying contact, a transfer contact and an arcing horn, a fixed arcing horn connected to the fixed contact terminal, a magnetic blowout coil electrically interconnecting said fixed arcing horn and said fixed terminal, one of said arcing horns having a portion operable within a slot-like recess in the other and forming therewith a short arc gap, one end of said recess being closely adjacent to the point of separation of said transfer contacts, and means for opening said circuit breaker to cause separation of said main current carrying contacts and transfer of the power current arc to said arcing horn portions across said short gap, said blowout coil being thereby connected in the circuit to cause extension of said are from said gap along said horns.

4. An electric circuit breaker comprising fixed contact structure including a main current carrying contact and a pivoted transfer contact, a pivoted movable contact structure coacting therewith including a. main current carrying contact,

and a transfer contact terminating in an arcing horn, a fixed arcing horn, a magnetic blowout coil electrically interconnecting said fixed arcing horn and the fixed contact terminal, the movable arcing horn having a fin-like arcing portion movable within a slot-like recess in said fixed horn and forming therebetween a short U-shape arc gap, and means for opening said circuit breaker to cause separation of said main current carrying contacts for transferring the power current are to said arcing horn portions across said short gap, said blowout coil being thereby connected in the circuit to cause extension of said are along said horns.

5. An electric circuit breaker comprising fixed contact structure including a main current carrying contact and a transfer contact, coacting movable contact structure including a main current carrying contact, a transfer contact and an arcing horn, an arc chute having a fixed arcing horn, a magnetic blowout coil electrically interconnecting said fixed arcing horn and the fixed contact terminal, said arcing horns having close, ly positioned interleaved arcing portions forming therebetween a short U-shaped arc gap, one end of said gap being closely adjacent to the point of separation of said transfer contacts, and means for opening said circuit breaker to cause in succession separation of said main current carrying contacts thereby transferring the power current to said transfer contacts, separation of said transfer contacts thereby initially forming the power current arc, and relative movement of said arcing portions to cause said are to transfer to said short gap across said arcing horns, said blowout coil being thereby connected in the circuit to cause extension of said arc along said horns into said are chute.

6. .An electric circuit breaker comprising relatively fixed and movable contact structure, a fixed arcing horn associated with said fixed contact structure, a coacting arcing horn carried by and movable with said movable contact structure, coacting primary current-carrying contacts mounted on said fixed and movable contact structure respectively, and coacting transfer contacts also mounted on said fixed and movable contact structures respectively and arranged to separate after separation of said primary contacts, the movable transfer contact comprising the butt end of said movable arcing horn at which initial arcing takes place.

7. An electric circuit breaker comprising relatively fixed and movable contact structure, a fixed arcing horn associated with said fixed contact structure, said arcing horn having a slot-like recess along the arcing face thereof, a coacting arcing horn carried by said movable contact structure and movable within said recess, coacting pri- CERTIFICATE OF CORRECTION. Patent No. 2,555,068. November 25, 19h}.

LEONARD J. LINDE.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, sec- 0nd column, line 56-37, claim 1, for "coating" read --coacting-; line 11.6, claim 2, for bread -'s1ot-1ike--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 25th day of January, A. D. 19141;.

Henry Van Arsdale,

(Seal) Acting Commissioner of Patents.

7 CERTIFICATE or CORRECTION. Patent No. 2,535,068. November 25, 1915.

LEONARD J. LmnE.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 56-57, claim 1, for coating read --coacting-; line k6, claim 2, for l b-11 read --'-s1ot-1ike--; and that the said Letters Pat ent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 25th day of January, A. D. 191411..

Henry Van Are dale,

(Seal) v Acting Commissioner of Patents. 

